Incremental Dynamic Analysis (IDA) is applied in a Performance-Based Earthquake Engineering context to investigate expected structural response, damage outcomes, and financial loss from highway bridges. This quantitative risk analysis procedure consists of: adopting a suitable suite of ground motions and performing IDA on a nonlinear model of the prototype structure; summarize and parameterize the IDA results into various percentile performance bounds; and integrate the results with respect to hazard intensity-recurrence relations into a probabilistic risk format. An illustrative example of the procedure is given for reinforced concrete highway bridge piers, designed to New Zealand, Japan and Caltrans specifications. It is shown that bridges designed to a "Design Basis Earthquake" that has a 10 percent probability in 50 years with PGA = 0.4g, and detailed according to the specification of each country, should perform well without extensive damage. However, if a larger earthquake occurs, such as a maximum considered event which has a probability of 2 percent in 50 years, then extensive damage with the possibility of collapse may be expected. The financial implications of this vulnerability are also given, revealing a four fold variation between the three countries.

SummaryA method is established to identify critical earthquake ground motions that are to be used in physical testing or subsequent advanced computational studies to enable seismic performance to be assessed. The ground motion identification procedure consists of: choosing a suitable suite of ground motions and an appropriate intensity measure; selecting a computational tool and modelling the structure accordingly; performing Incremental Dynamic Analysis on a nonlinear model of the structure; interpreting these results into 50 th (median) and 90 th percentile performance bounds; and identifying the critical ground motions that are close to these defining probabilistic curves at ground motion intensities corresponding to the design basis earthquake and the maximum considered earthquake. An illustrative example of the procedure is given for a reinforced concrete highway bridge pier designed to New Zealand specifications. Pseudodynamic tests and finite element based time history analyses are performed on the pier using three earthquake ground motions identified as: (i) a Design Basis Earthquake (10% probability in 50 years) with 90 percent confidence of non-exceedance; (ii) a Maximum Considered Event (2% probability in 50 years) representing a median response; and (iii) a Maximum Considered Event representing 90 percent confidence of non-exceedance.

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Circular reinforced concrete highway bridge piers, designed in accordance with the requirements of Caltrans, New Zealand and Japanese specifications, are experimentally investigated to assess their seismic performance. Pseudodynamic test procedures are developed to perform experiments on 30% scaled models of the three prototype bridge piers. Each specimen is subjected to a sequence of three different earthquake ground motions scaled appropriately to represent: (i) the Design Basis Earthquake (DBE) with a 90 percent non-exceedance probability; (ii) the Maximum Considered Earthquake (MCE) with a 50 percent non-exceedance probability; and (iii) the MCE with a 90 percent non-exceedance probability. Damage states after the earthquakes are assessed and mapped for seismic risk assessment. The damage outcomes and the corresponding seismic risks validate the objectives of the performance based design codes of the three countries. The results show that when bridge piers are designed to the specifications of each of the three countries, satisfactory performance with only slight to moderate damage can be expected for DBE. For the MCE, severe damage without collapse is likely for the Caltrans and Japanese piers. However, the NZ pier may not be able to survive MCE motions with sufficient reliability to ensure the preservation of life-safety. IntroductionRecent major earthquakes such as the 1994 Northridge and the 1995 Hyogoken-Nanbu (Kobe) events had a severe impact on the serviceability of bridges. Consequently, there has been a growing interest in comparing the seismic performance of bridges designed according to the codes and standards of different countries. This is because both the loading requirements and structural detailing procedures vary considerably, even though the magnitude of hazard exposure may be similar. As part of a cooperative four-country international project, Tanabe [1999] designed four bridge piers, in accordance with Caltrans, New Zealand, Japanese and European design standards. The main purpose of this international project was to identify differences in the cross-section dimensions and reinforcing details, to clarify the reasons for these differences, and to assess the likely seismic performance by computational means. This previous comparative research was restricted to uni-directional earthquake motions. Given that simultaneous bidirectional earthquake motions occur in reality, and computational predictions may differ from real response due to modelling simplifications, it is considered desirable to conduct an experimental investigation of the seismic response of bridge piers including bi-directional effects.Although simplified test procedures such as quasi-static and high-speed cyclic tests [Dhakal and Pan 2003] exist for general experimental studies of structural behaviour, more advanced test procedures such as pseudo-dynamic tests (referred to as PD tests hereafter) or shaking table tests are needed to experimentally assess the expected seismic performance of structures. PD tests offe...